WASHINGTON (CNN) -- Most Americans are angry about "something" when it comes to how the country is run, and they are more likely than in previous years to vote for a challenger this November, a new poll suggests.

A majority of Americans surveyed -- and a higher percentage than recorded during the same time last year -- said things in the United States are going "badly." Among this year's respondents, 29 percent said "pretty badly" and 25 percent -- up from 15 percent a month ago -- answered "very badly." By comparison, 37 percent described the way things are going as "fairly well," and 9 percent answered "very well."

Of these people, 76 percent said there was "something" to be angry about in the country today. By comparison, 59 percent felt that way when polled in February. (Watch Bill Schneider's take on angry voters -- 1:40)

Only 21 percent said they were "generally content" in the latest poll.

Nine percent said they considered the economy to be "very good," a number unchanged from a June CNN poll. But the number who considered conditions "somewhat good" dropped from 42 percent to 35 percent over the same period.

The number of respondents who consider the economy "somewhat poor" rose from 31 percent to 34 percent, and the number who called the economy "very poor" jumped from 16 percent to 22 percent.

A majority -- 55 percent -- said they are more likely to back a challenger in races on this year's ballot. Such anti-incumbent sentiment is higher than the 48 percent recorded as "pro-challenger" in a similar survey in 1994, when the GOP took control of both houses of Congress.

Nonetheless, 48 percent said that, if most of the present members of Congress were replaced with new members, there would be no difference. By contrast, 42 percent said such a scenario would change Congress for the better, and 7 percent said it would change Congress for the worse.

The results, based on a half-sample of 1,004 adult Americans polled by Opinion Research Corporation for CNN Wednesday through Saturday have a margin of sampling error of plus or minus 4.5 percentage points.

More than 60 percent of those surveyed said government policies need either major changes or a complete overhaul, while 30 percent said minor changes were needed. Only 7 percent said no change is necessary.

The economy topped the list of respondents' concerns, with 28 percent calling it the most important issue when deciding how to cast their ballots. Coming second was Iraq at 25 percent, followed by terrorism (18 percent), moral issues (15 percent) and immigration (14 percent). (Watch Bush dispute idea that Iraq is in civil war - 4:09)

Democrats lead Republicans by a 10-point margin, 53 to 43 percent, among likely voters asked which party's congressional candidate they would support in November, and Democrats held a 56-40 lead on the same question among registered voters.

The survey has a sampling error of 3 percentage points among the full group and 4 percentage points among likely voters.

Nearly half of the respondents -- 49 percent -- said they considered the GOP the party of strong leadership. But 56 percent said they considered the Democrats the party of change, with 49 percent considering them the more forward-looking party.